This study emphasise the importance of controlling weeds chemically during grapevine bud break.
Two weed management practices were applied, as described in Table 1. The trial was conducted over four seasons (2009/10 to 2012/13) in a full-bearing, seven-year-old drip irrigated Shiraz/101-14 Mgt vineyard established on a sandy (0 to 300 mm soil layer) to sandy clay loam (300 to 600 mm soil layer) soil near Stellenbosch. The vines were spaced 1.2 m in the row and 2.5 m between rows and trained onto a vertical shoot positioning (VSP) trellis system. The annual rainfall averaged 673 mm, of which approximately 73% precipitated from March to August.
Grapevine vegetative growth and yield
The average shoot mass of the grapevines where CC (for explanation, see Table 1) was applied was significantly higher than where MC (for explanation, see Table 1) was applied (Figure 1). Similar to the shoot mass, the yield of the grapevines where CC was applied, was significantly higher than where MC was applied (Figure 2).
FIGURE 1. The effect of CC and MC on the average shoot mass (2009/10 to 2012/13 seasons) of a drip irrigated Shiraz/101-14 Mgt vineyard established on a sandy to sandy clay loam soil near Stellenbosch. For detailed information on CC and MC, see Table 1.
FIGURE 2. The effect of CC and MC on the average yield (2009/10 to 2012/13 seasons) of a drip irrigated Shiraz/101-14 Mgt vineyard established on a sandy to sandy clay loam soil near Stellenbosch. For detailed information on CC and MC, see Table 1.
Incorporating the aboveground growth of the weeds and the cover crops mechanically in the work row during grapevine bud break decreased the vegetative growth and yield of the grapevines compared to that of the vineyard in which full surface chemical weed control was applied. This supports the results of studies done in micro-irrigated wine grape vineyards.
Incorporating the aboveground growth (weeds and cover crops) mechanically during grapevine bud break decreased grapevine shoot mass and yield. The importance of controlling the cover crops or weeds chemically during grapevine bud break was illustrated. These results support the trends observed in grapevines under micro-sprinkler irrigation.
The author thanks the ARC, Winetech and Dried Fruit Technical Services for financial support, the staff of the Soil and Water Science Department at ARC Infruitec-Nietvoorbij for technical support and Blaauwklippen Wine Estate for supplying the trial site and farm support.
– For more information, contact Johan Fourie at FourieJ@arc.agric.za.